Could be a good year for Lyme disease

If personal experience and reader reports are reliable indicators, this summer could be a bad one for ticks and Lyme disease. Since early April, I've removed countless ticks from my clothing, and several have been attached at the base of the hairline on my neck.

Likewise, I've heard from many readers since late winter who have returned from hunting trips with dogs covered with ticks. One hunter was so frustrated by the abundance of ticks, he told me he wasn't going to take his dogs out again until the problem eased.

Fortunately, effective tick prevention medications for dogs are readily available from veterinarians. I can't remember the last time I removed an attached tick from my dog.

We humans, on the other hand, must be more proactive and check for ticks after every outdoor adventure. Ticks cling to the ends of grasses and other vegetation waiting for warm-blooded hosts to pass by. Immature ticks are small and difficult to notice. Fortunately blacklegged ticks (Ixodes scapularis, formerly called deer ticks) must be attached for at least 36 to 48 hours for the Lyme disease bacterium (Borrelia burgdorferi) to be transmitted.

An obvious question regarding the transmission of Lyme disease is why it takes more than a day for ticks to transmit the disease. When a tick attaches to a human host, the bacterial spirochetes live in the tick's midgut. Over the next 18 hours, as the tick feeds, blood enters the midgut. Then the spirochetes begin to multiply and become infectious. About 24 hours after attachment, infectious spirochetes migrate to the tick's salivary glands. Then, 36 to 48 hours after attachment, infectious spirochetes are injected into the host. Over the next week the spirochetes spread throughout the host's body, and symptoms ensue.

This explains why attached ticks removed within 24 hours are unlikely to infect victims with Lyme disease. The spirochetes have not yet reached the host's bloodstream. This is also why attached ticks should not be removed with fingers. Getting a good grip often requires squeezing the tick, which effectively transforms the tick into a hypodermic needle. Squeezing an engorged tick forces its infected saliva into the host. Remove attached ticks with fine tweezers as described below.

According to the New England Journal of Medicine, Lyme disease is the most common vector-borne disease in the United States. In 2011, there were 24,364 confirmed cases nationwide. Hot spots include Pennsylvania (with 4,739 confirmed cases), New Jersey (3,398), New York (3,118), Wisconsin (2,408), Connecticut (2,004), Minnesota (1,185), Massachusetts (1,801), Maryland (938), New Hampshire (887), Maine (801), Delaware (767), and Virginia (756). Though Lyme disease can be prevented by vaccination, it is prohibitively expensive and less than 100 percent effective.

The Centers for Disease Control and Prevention (www.cdc.gov) report that most cases of Lyme disease can be treated successfully with a few weeks of antibiotics. A better, more effective treatment for Lyme disease is prevention.

Avoid tall grass and dense woody vegetation. Use a DEET-based repellent on clothes and exposed skin. Or wear clothing treated with long-lasting tick repellents. Tuck pant legs into socks and wrap in duck tape. Do frequent tick checks, even while in your own backyard.

And don't forget to check the car. After a field trip to a favorite park or wild area, ticks can get into a pile of sweatshirts or slip into joints in the upholstery where they can stay alive for months. So shake off all clothing before throwing it into the back seat.

If you find an attached tick, here's advice from the CDC. Do not squeeze the tick and pull it out with your fingers. This only forces possibly infected blood into the bite site.

Instead, use a fine tipped tweezer to grasp the tick as close to the skin's surface as possible. Pull upward with steady, even pressure. If the mouthparts break off, remove them with the tweezers. Then clean the area with rubbing alcohol and soap and water.

And if a few days later you find a tell-tale bull's-eye rash, or develop symptoms such as chills, fever, headache, achy muscles, swollen lymph nodes, and/or fatigue, see a physician familiar with Lyme disease.